A laser processing device irradiates a laser beam emitted from a laser oscillator to an object to be processed by using an optical system, and performs a laser processing operation such as marking, exposure, etching, punching, scribing, or dicing on the object to be processed through irradiation of the laser beam.
Recently, a method of processing an object to be processed by forming a focusing point in the object to be processed through which a laser beam may be transmitted and forming cracks so as to prevent damage to a surface of the object to be processed has been spotlighted. For example, when a high-power laser beam is focused in a semiconductor wafer to form a focusing point, a modified area is formed around the focusing point and cracks are formed from the modified area. Next, when the laser beam moves along a processing line of the semiconductor wafer, a crack row may be formed in the object to be processed, and then the crack row may extend to a surface of the semiconductor wafer naturally or due to an external force, thereby making it possible to cut the semiconductor wafer.
In a laser processing device for performing a processing operation by forming a focusing point in an object to be processed, when a laser beam is incident on a modified area or a crack area formed by the focusing point, the laser beam is splashed around due to interference, thereby damaging the object to be processed. In particular, when the object to be processed is a semiconductor wafer on which elements are integrated and the splashed laser beam affects an active area where the elements are located, a semiconductor chip may be damaged, thereby greatly reducing the yield of the semiconductor chip. Accordingly, it is necessary to automatically inspect and manage the laser processing device so as to early detect damage to the object to be processed due to the splashed laser beam.